LOS ANGELES (AP) — A small fire that broke out on a Southwest Airlines plane at a Southern California airport led to a confusing and sometimes chaotic evacuation, with some fearful travelers pushing each other to reach the exit, passengers said Tuesday.

Lauren Barnett was sitting toward the back of the Boeing 737 as it headed to the runway at John Wayne Airport in Santa Ana when she heard a noise that sounded like a car backfiring. That's when the power went out.

Soon afterward, someone said smoke was coming from the plane Monday evening and another person shouted that everyone needed to evacuate, said Barnett, a 30-year-old concierge from San Jose.

"Everyone went into a panic at that point," she said, with some passengers struggling to open overhead bins to retrieve their belongings. "Some of us were screaming, 'Leave your suitcases!'"

When an emergency slide deployed, it made an unfamiliar sound that frightened some passengers, and one person screamed out.

"It set off another panic," Barnett said. "People started pushing, and it got a little scary."

She said everyone soon calmed down and got off the plane.

All 139 passengers and five crew members made it safely off the plane, and the flames were out by the time airport fire crews arrived minutes later, airport spokeswoman Deanne Thompson said.

One of the four emergency slides failed to deploy, but it didn't hinder the evacuation, she said. A few passengers reported minor scrapes, but there were no serious injuries.

Passenger JC Arkham said things were not as scary in his part of the plane but described it as tense and confusing. He was in an exit row with his wife when he heard a loud pop and the power went out.

"Twenty seconds later, one of the flight attendants at the front of the plane starts shouting, 'Evacuate, evacuate, evacuate!'" he said. "Then another flight attendant ordered me to pop open the door."

Arkham said he opened the door, stepped out on the wing and then began helping his family and other passengers out of the plane.

"Getting out on the wing of the plane, I'm looking around and going, 'Wow, this is really happening,'" he said. "It was really very surreal."

His wife fell on the wing, which was slippery from emergency sprinklers, but only had a minor arm injury.

About a half dozen people were on the wing when a ground crew member ordered them to get back in the plane and go down the slide, Arkham said.

The passengers were put on another flight to San Jose, which arrived shortly after midnight, Southwest Airlines spokeswoman Michelle Agnew said.

The fire was in the airliner's auxiliary power unit and was extinguished by the plane's fire suppression system, according to Federal Aviation Administration spokesman Allen Kenitzer.

The unit provides power to start the aircraft's main engines and serves as backup power in some situations.